import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class TcpEchoServer {
    private ServerSocket serverSocket = null;

    public TcpEchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }

    public void start() throws IOException {
        ExecutorService executorService = Executors.newCachedThreadPool();
        System.out.println("服务器启动！");
        while(true){
            Socket clientSocket = serverSocket.accept();
            executorService.submit(new Runnable() {
                @Override
                public void run() {
                    try {
                        processConnection(clientSocket);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            });

        }
    }

    private void processConnection(Socket clientSocket) throws IOException {
        System.out.printf("[%s: %d] 客户端上线！\n", clientSocket.getInetAddress().toString(), clientSocket.getPort());
        try(InputStream inputStream = clientSocket.getInputStream(); OutputStream outputStream = clientSocket.getOutputStream()){
            Scanner scanner = new Scanner(inputStream);
            PrintWriter printWriter = new PrintWriter(outputStream);
            while(true){
                if(!scanner.hasNext()){
                    System.out.printf("[%s:%d] 客户端下线！\n", clientSocket.getInetAddress().toString(), clientSocket.getPort());
                    break;
                }

                String request = scanner.next();
                String response = process(request);

                printWriter.println(response);
                printWriter.flush();

                System.out.printf("[%s : %d] req: %s; resp: %s\n", clientSocket.getInetAddress().toString(), clientSocket.getPort(), request, response);
            }
        }catch (IOException e){
            e.printStackTrace();
        }finally {
            clientSocket.close();
        }
    }

    private String process(String request){
        return request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer tcpEchoServer = new TcpEchoServer(8090);
        tcpEchoServer.start();
    }
}
